Shuttling movement

Figure 6.8 Structural formula of the rotaxane 96+ and schematic representation of the intramolecular (below left) and sacrificial (below right) mechanisms for the photoinduced shuttling movement of macrocycle between the two stations A1 and A2.

Scheme 12 Photochemically driven shuttling movement of an a-cyclodextrin in an azobenzene-containing thread through reversible E/Z photoisomerization [61]...

A shuttle movement of the guest molecule has been observed the guest stays at a fixed position in the tube, shuttles on the NMR time scale at 60 °C, and rapidly moves or partially leaves above 60 °C. NMR studies of nanotube 25 revealed that it is a 1 1 mixture of structural isomers 25a and 25b (Scheme 9). In isomer 25b, each ligand is placed in a C2-symmetry and only seven protons corresponding to half of 25b were observed. On the other hand, in isomer 25b, all 14 protons were observed as the C2-symmetry of the ligands was destroyed. The tubes 25b and 24 were characterized by X-ray crystallog-... 

Fig. 6 The intramolecular mechanisms for the photo induced shuttling movement of macrocycle R between the two stations Aj and A2 in rotaxane 1. View this art in color at www.dekker.com.)...

Figure 14b). a-CyD resides at the azobenzene part when it takes the trans-form, while photoisomerization to the dMorm pushes it to one of the methylene chains. CD absorption is always active in 25, but the location of a-CyD dramatically influences the ICD spectral shape. Hence, the shuttle movement of 25 can also be observed by CD spectroscopy. ... 

The strategy devised in order to obtain the photoinduced shuttling movement of R between the two stations Ai + and A2 + is based on a four stroke synchronized sequence of electron transfer and molecular rearrangement processes, as illustrated in Figure 27(b).Light excitation of the photoactive unit P + (process 1) is followed by the transfer of an electron from this unit to Ai + (process 2) which competes with the intrinsic decay of the P + excited state (process 3). After the reduction of Ai +, with the consequent deactivation of this station, the ring moves (process 4) by 1.3 nm to encircle A2 +, a step that is in competition with the back electron transfer from Ai+ (still encircled by R) to the oxidized unit P + (process 5). Eventually, a back electron transfer from the free reduced station Ai + to the oxidized unit P + (process 6) restores the electron-acceptor power to this radical cationic station. As... 

Shuttle Kiln. An intermittent bogie kiln consisting of a box-like structure with doors at each end and accommodating kiln cars (usually two in number). Pottery-ware is set on the refractory decks of the cars which are then pushed along rails into the kiln, displacing two other cars of fired ware from the kiln. The fired ware is taken from the displaced cars which are then re-set with more ware to be fired. The shuttle movement of the kiln cars is is then repeated (cf. bogie kiln). 

During the interlacing or the chaining process, different tensions appear in the thread by the take-up lever and/or shuttle movement. The thread tighteners are responsible for many different tasks. On the one hand they control the holding of... 

NHs and nonbonded ones and the whole spectra corresponded to centrodimeric structures with i synunetiy due to prohibition of the shuttle movement. The lengths of the oligomers, i.e., the numbers of intermolecular hydrogen bonds in the duplexes, affected the coalesced temperatures for 36a with 6 hydrogen bonds, 223 K for 36b with 10 hydrogen bonds, 283 K for 36c with 14 hydrogen bonds, >318 K [32]. 

An ureido-dipeptide based duplex was reported by Hirao et al. (Fig.4.23) [50]. X-ray single crystal analysis showed that two molecules formed a right-handed helical stmcmre. The chirality center of the amino acid side chains induced this supramolecular chirality. The dimerization constant was determined to be 2.9 X 10" M by H NMR dilution experiments. Interestingly, variable H NMR experiments revealed a unique shuttle movement as depicted in Fig. 4.23. 

For optimising the cam design, a detailed dynamic model of the picking mechanism as shown in Fig. 5 was constructed and cams of linear, cosine and polynomial profiles were designed [2]. The characteristics of cam and shuttle movements from the mathematical equations in Table 1 were calculated for these three types of cams using computer. To obtain functionally correct and accurate profile, the cams were plotted on a computer using the principle of envelopes [3]. The actual procedure is as follows Referring to Fig, 6, for the overpick cam mechanism,the... 

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